Solid electrolytic capacitor and method of manufacturing the capacitor

ABSTRACT

A solid electrolytic capacitor having a high capacitance and excellent high frequency response including a valve metal sheet which is made porous, a dielectric layer formed on the porous portion, a solid electrolyte layer formed on the dielectric layer, a collector layer and an electrode exposure area formed on the solid electrolyte layer, and an insulating section electrically insulating the electrode exposure area from the collector layer, in which the electrode exposure area and the collector layer are formed on the same surface of the valve metal sheet.

FIELD OF THE INVENTION

The present invention relates to a solid electrolytic capacitor for usein a variety of electronic equipment and a manufacturing method thereof

BACKGROUND OF THE INVENTION

In recent years, as a reduction in size and operation at higherfrequencies are required of electronic equipment, a large capacitancefor the smallest possible size, a low ESR(equivalent series resistance)and a low ESL(equivalent series inductance) are required for capacitorsused in electronic equipment. As a large capacitance multi-layer solidelectrolytic capacitor, chip type capacitors as disclosed in the U.S.Pat. No. 5,377,073 and the Japanese Patent Laid-Open Publication No.H11-274002 have been so far known. However, these prior art solidelectrolytic capacitors incorporate terminals, lead wires and the likefor electric connections and also for mounting on a circuit board,resulting in forming resistance and inductance components to prevent thecapacitors from reducing the ESL further.

The present invention deals with the conventional problems as describedabove and aims to provide a large capacitance solid electrolyticcapacitor with excellent high frequency response, which can be mountedon a circuit board and directly connected with semiconductor devices,and a method of manufacturing the same.

DISCLOSURE OF THE INVENTION

The present invention discloses a capacitor element and a solidelectrolytic capacitor composed of a plurality of the capacitor elementslaminated on top of each other in layers, the capacitor elementcomprising:

a valve metal sheet having a porous section;

an electrode exposure area formed on one surface of the valve metalsheet;

a dielectric layer formed on the porous section of the valve metalsheet;

a solid electrolyte layer formed on the dielectric layer; and

a collector layer formed on the solid electrolyte layer,

wherein the electrode exposure area and collector layer are formed onthe same surface of the valve metal sheet and electrically insulatedfrom each other by an insulating section.

Semiconductor devices can be directly mounted on the solid electrolyticcapacitor of the present invention. Thus, the capacitor does not needconventionally needed connection terminals and lead wires and has anexcellent high frequency response.

Also, the present invention discloses a method of manufacturing theforegoing solid electrolytic capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a solid electrolytic capacitor inexemplary embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view of the solid electrolytic capacitor inexemplary embodiment 1 of the present invention.

FIG. 3 is a partially enlarged cross-sectional view of the solidelectrolytic capacitor in exemplary embodiment 1 of the presentinvention.

FIG. 4 is a partially enlarged cross-sectional view of the solidelectrolytic capacitors in exemplary embodiment 1 and 6 of the presentinvention.

FIG. 5 is a top view of solid electrolytic capacitors in exemplaryembodiments 2 and 7 of the present invention.

FIG. 6 is a cross-sectional view of the solid electrolytic capacitors inexemplary embodiments 2 and 7 of the present invention.

FIG. 7 is a cross-sectional view of the solid electrolytic capacitors inexemplary embodiments 2 and 7 of the present invention to show anotherelectrode configuration.

FIG. 8 is a cross-sectional view of the solid electrolytic capacitors inexemplary embodiments 2 and 7 of the present invention to show stillanother electrode configuration.

FIG. 9 is a cross-sectional view of the capacitor element of solidelectrolytic capacitors in exemplary embodiments 3 and 8 of the presentinvention.

FIG. 10 is a cross-sectional view of aluminum foil in exemplaryembodiment 4 of the present invention.

FIG. 11 is a cross-sectional view showing a state of a resist filmformed on the aluminum foil in exemplary embodiment 4 of the presentinvention.

FIG. 12 is a cross-sectional view of a valve metal sheet by makingaluminum foil porous, in exemplary embodiment 4 of the presentinvention.

FIG. 13 is a cross-sectional view showing a state of a dielectric layerformed on the porous valve metal sheet in exemplary embodiment 4 of thepresent invention.

FIG. 14 is a cross-sectional view showing a state of an insulatingsection formed on the porous valve metal sheet in exemplary embodiment 4of the present invention.

FIG. 15 is a cross-sectional view showing a state of a solid electrolytelayer formed on the porous valve metal sheet in exemplary embodiment 4of the present invention.

FIG. 16 is a cross-sectional view showing the state of the resist filmremoved from the porous valve metal sheet in exemplary embodiment 4 ofthe present invention.

FIG. 17 is a cross-sectional view of a capacitor element having a firstconnection terminal and a second connection terminal formed on the valvemetal sheet in exemplary embodiment 4 of the present invention.

FIG. 18 is a cross-sectional view showing the state of a package formedaround a periphery and beneath a bottom surface of the capacitor elementin exemplary embodiment 4 of the present invention.

FIG. 19 is a cross-sectional view showing the state of a blind holeformed in the package beneath the bottom surface of the capacitorelement in exemplary embodiment 4 of the present invention.

FIG. 20 is a cross-sectional view showing a state of the capacitorelement further provided with lead out electrodes formed in the blindholes and an additional package to electrically insulate the lead outelectrodes formed beneath the bottom surface in exemplary embodiment 4of the present invention.

FIG. 21 is a cross-sectional view of a solid electrolytic capacitorobtained by providing external connection terminals on the capacitorelement in exemplary embodiment 4 of the present invention.

FIG. 22 is a cross-sectional view of a tantalum sintered body fordescribing a manufacturing method of a solid electrolytic capacitor inexemplary embodiment 5 of the present invention.

FIG. 23 is a cross-sectional view showing a step of forming electrodeportions on the tantalum sintered body in exemplary embodiment 5 of thepresent invention.

FIG. 24 is a cross-sectional view showing a state of a dielectric layerformed on the tantalum sintered body in exemplary embodiment 5 of thepresent invention.

FIG. 25 is a cross-sectional view showing the state of an insulatingsection formed on the tantalum sintered body in exemplary embodiment 5of the present invention.

FIG. 26 is a cross-sectional view showing a state of a solid electrolytelayer and a collector layer formed on the tantalum sintered body inexemplary embodiment 5 of the present invention

FIG. 27 is a cross-sectional view showing a state of the resist filmremoved in exemplary embodiment 5 of the present invention.

FIG. 28 is a cross-sectional view of a capacitor element in exemplaryembodiment 5 of the present invention.

FIG. 29 is a cross-sectional view of a solid electrolytic capacitorproduced by providing a package on the capacitor element in exemplaryembodiment 5 of the present invention.

FIG. 30 is a perspective view of a solid electrolytic capacitor inexemplary embodiment 6 of the present invention.

FIG. 31 is a cross-sectional view of the solid electrolytic capacitor inexemplary embodiment 6 of the present invention.

FIG. 32 is a cross-sectional view of a solid electrolytic capacitor inexemplary embodiment 7 of the present invention.

FIG. 33 is a cross-sectional view of another solid electrolyticcapacitor in exemplary embodiment 7 of the present invention.

FIG. 34 is a cross-sectional view of still another solid electrolyticcapacitor in exemplary embodiment 7 of the present invention.

FIG. 35 is a cross-sectional view showing a state of capacitor elementslaminated in exemplary embodiment 9 of the present invention.

FIG. 36 is a cross-sectional view of a solid electrolytic capacitor inexemplary embodiment 9 of the present invention.

FIG. 37 is cross-sectional view of a solid electrolytic capacitorproduced by laminating capacitor elements in exemplary embodiment 10 ofthe present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a description is given to a solid electrolytic capacitor and amanufacturing method thereof with reference to the drawings. Thedrawings are schematic and it should be noticed that relativedimensional relationships of the respective elements are not shown toscale.

Exemplary Embodiment 1

In FIG. 1 through FIG. 4, a capacitor element 1 comprises a valve metalsheet 3 that is made porous except for a plurality of electrode portions2, a dielectric layer 4 formed on the porous surface of the valve metalsheet 3, solid electrolyte layers 5 formed on the dielectric layer 4,collector layers 6 formed on the solid electrolyte layer 5 and aninsulating section 7 disposed between the electrode portion 2 and thecollector layer 6. Here, an area where the electrode portion 2 isexposed is referred to as an electrode exposure area 25. The electrodeexposure area 25 and the collector layer 6 are situated on the samesurface of the valve metal sheet 3 and electrically insulated from eachother by insulating section 7.

Although the capacitor element 1 functions with the aforementionedstructure, it is preferred that an additional metal layer is formed onthe electrode exposure area 25 to make first connection terminal 8 andanother additional metal layer is formed on the collector layer 6 aroundthe insulating section 7 to make second connection terminal 9.

Around an outer periphery of the capacitor element 1 thus structured isformed package 11 composed of epoxy resin and the like by a moldingprocess to complete a solid electrolytic capacitor.

As the valve metal sheet 3, an aluminum foil is used and is made porousby etching except the areas corresponding to the electrode portions 2and the dielectric layer 4 can be formed on the surface and the poroussurface of the aluminum foil by anodizing in a forming solution.

Further, as the solid electrolyte layer 5, a conductive high polymerlayer formed of functional polymers such as polypyrrole, polythiopheneand the like formed by a chemical oxidation polymerization or by anelectrolytic polymerization can be used, or a manganese dioxide layerformed by impregnating manganese nitrate solution and a followingthermal decomposition, and the like can be used.

Furthermore, as the collector layer 6, a carbon layer alone or alaminated structure of a carbon layer and a silver paste layer can beused.

In addition, as the insulating section 7, a silicone resin that isexcellent in printability, water repellency and the like can be used.Also, an epoxy resin and a fluorocarbon resin can be used.

In order to enhance printability, water repellency and the like, acomposite with necessary additives contained can also be used.

As the first connection terminal 8 and the second connection terminal 9metals such as copper, solder, silver, gold, nickel and the like can beused in a single layer or in a laminated structure of these metals.

When the first connection terminal 8 is formed on the electrode exposurearea 25, a surface roughening process to provide asperity 12 on theelectrode exposure area 25, as shown in FIG. 4, strongly bonds the firstconnection terminal 8 to the electrode exposure area 25, therebyenabling increased reliability in electrical connection.

A solid electrolytic capacitor thus structured has a plurality ofconnection terminals 8 and connection terminals 9 on the upper andbottom surfaces thereof, as FIG. 1 and FIG. 2 show. This structureallows one surface thereof to be mounted with semiconductor devices andanother surface to be connected to lands of a circuit board.

A number of the connection terminals 8 and 9 is made the same as anumber of connecting bumps of the semiconductor devices. When the numberof connection terminals 8 and 9 exceeds the number of connecting bumpsof the semiconductor devices, chip type components such as chipresistors, chip capacitors, chip inductors and the like can be mountedon the one surface of the solid electrolytic capacitor in addition tothe semiconductor devices, thereby allowing the whole assembly to be acircuit module.

Also, first lead out electrode 22 and second lead out electrode 23 areprovided in the package beneath the bottom surface of the capacitor andare connected to external terminals 24, respectively, as required.

However, these lead out electrodes and external terminals are notnecessarily required and the most appropriate structure can be employedaccording to a circuit design and a mounting process.

Exemplary Embodiment 2

A solid electrolytic capacitor in exemplary embodiment 2 of the presentinvention is similar to the one in exemplary embodiment 1 as far as thefundamental structure is concerned. A different point is to haveconnection bumps 13 and 14 made of gold, solder or tin provided on thefirst connection terminal 8 and the second connection terminal 9,respectively, so as to facilitate the connection with the semiconductordevices. In order to keep the bump pitches constant, connection bumps 13and 14 are formed after insulating layer 16 with openings 15 provided atplaces, where connection bumps 13 and 14 are located, is formed.

As a result of disposing connection terminals 8 and connection terminals9 alternately on the same surface of a sheet-like solid electrolyticcapacitor, a low ESR as well as a low ESL can be obtained, therebyallowing the solid electrolytic capacitor to have an excellent highfrequency response.

A solid electrolytic capacitor as shown in FIG. 6 is a sheet-like solidelectrolytic capacitor structured to have connection bumps 13 and 14disposed on both surfaces thereof.

It is also possible to have connection bumps 13 and 14 disposed only onthe upper surface of the solid electrolytic capacitor and to have thebottom surface thereof covered with package 11 as shown in FIG. 2. Thisstructure allows the solid electrolytic capacitor to be mounted on acircuit board of high density wiring patterns with an insulatingcondition maintained

A description is given to another configuration of the electrode portionwith reference to FIG. 7 and FIG. 8.

A solid electrolytic capacitor as shown in FIG. 7 has electrode portions2 with cross-sectional areas made smaller than the areas of theelectrode exposure area 25 in the valve metal sheet 3, thereby allowingthe capacitance of the capacitor to increase. The crossectional area ofthe electrode portions 2 can be controlled by controlling the etchingconditions of the valve metal sheet.

The electrode portion 2 shown in FIG. 8 is formed so as to extend to anarbitrary depth in valve sheet metal 3, thereby allowing the capacitanceof the capacitor to increase further.

Accordingly, the solid electrolytic capacitor in the present exemplaryembodiment is allowed to have semiconductor devices mounted thereon andalso to be easily mounted on a circuit board due to the provision of theconnection terminals 8 and 9 and the connection bumps 13 and 14 disposedthereon, respectively. And this structure contributes to obtaining alarge capacitance capacitor with the smallest possible configuration incomparison with the prior art capacitors. As a result, considerableprogress is made toward a size reduction and enhanced mountingefficiency.

Exemplary Embodiment 3

A description is given to a solid electrolytic capacitor in exemplaryembodiment 3 of the present invention with reference to FIG. 9. As FIG.9 shows, capacitor element 1 in the present exemplary embodimentcomprises a valve metal sheet 3 prepared by forming a tantalum powderinto a sheet-like shape followed by a sintering, a dielectric layerformed by an anodization on a portion other than an electrode exposurearea 25, by preventing an invasion of forming solution by a resist filmformed on the area of valve metal sheet 3, a solid electrolyte layerformed on the dielectric layer, the solid electrolyte layer beingcomposed of a conductive polymer or a manganese dioxide or the like, acollector layer formed on the solid electrolyte layer, the collectorlayer comprising carbon and a silver paste, an insulating section 7provided around the electrode exposure area 25, first connectionterminal 8 connected to the electrode portion 2, which is located insidethe insulating section 7, and second connection terminal 9 connected tothe collector layer, which is provided around the insulating section 7.

The capacitor element thus structured is formed with package 11 as FIG.1 shows, thereby completing a solid electrolytic capacitor.

The reason why such a sheet of sintered valve metal powder as describedabove is used is that a solid electrolytic capacitor with a largercapacitance can be obtained compared with the case where aluminum foilmade porous by etching is used.

With respect to the structure of valve metal sheet 3, there is anothermethod of forming electrode portion 2 by forming a through hole in thevalve metal sheet 3 in advance besides the method of preventing thedielectric layer from being formed by employing a resist and the like asdescribed above. In this case, a wall surface with no dielectric layeris formed inside of the through hole and a valve metal powder of thesame kind is pressed into the through hole, thereby forming theelectrode portion 2. As an alternate method of forming the electrodeportion 2 is a method of forming a metal layer on the inner walls of thethrough hole by plating.

Exemplary Embodiment 4

A description is given to a solid electrolytic capacitor in exemplaryembodiment 4 of the present invention with reference to FIG. 10 throughFIG. 21.

First, as FIG. 10 shows, aluminum foil 17 is prepared. Then, as FIG. 11shows, resist films 18 composed of a chemical-resistant photo-resist, amasking tape and the like are formed on both surfaces of the aluminumfoil 17 at positions where the electrode portions are formed and theresist films 18 thus formed are cured.

Next, as FIG. 12 shows, the aluminum foil 17 with the resist film 18formed is chemically etched to make the areas not covered with theresist film 18 porous. Thus, the valve metal sheet 3 with electrodeportion 2 formed on the areas, where resist film 18 is formed, isproduced.

Subsequently, the valve metal sheet 3 with resist film 18 left thereonas FIG. 13 shows is anodized in a forming solution, thereby forming adielectric layer 4 on the surface of the porous section of the valvemetal sheet 3 except the area where electrode portion 2 is formed.

Then, as FIG. 14 shows, insulating section 7 is formed around the resistfilm 18 by a printing method and the like to prevent short-circuitingbetween the electrode portion 2 and the collector layer 6 to be formedlater.

Next, the valve metal sheet 3 with insulating section 7 is immersed in asolution containing pyrrole as FIG. 15 shows and then immersed in anoxidizing solution to have a thin polypyrrole layer formed on thedielectric layer 4 by chemical oxidation polymerization.

Further, the valve metal sheet 3 with the thin polypyrrole Layer formedis immersed in a solution containing pyrrole to have a sufficientlythick polypyrrole layer formed on the thin polypyrrole layer by anelectrolytic polymerization. The electrolytic polymerization isperformed with the polypyrrole layer serving as a positive electrode andan electrode in the solution as a negative electrode. In this way, asolid electrolyte layer 5 of sufficiently thick polypyrrole layer formedon the thin polypyrrole layer is formed.

The resist layer 18 is removed after collector layer 6 comprising acarbon layer, a silver paste layer and the like is formed on the solidelectrolyte layer 5, as FIG. 16 shows.

Subsequently, as FIG. 17 shows, any one of electrode materials such asgold, silver, copper, nickel and the like is deposited on electrodeexposure area 25 and collector layer 6 by methods such as a vacuumdeposition, a sputtering, a plating and the like to form firstconnection terminal 8 formed on the electrode exposure area 25 andsecond connection terminal 9 on the collector layer 6, therebycompleting capacitor element 1.

Then, as FIG. 18 shows, package 11 composed of epoxy resin and the liketo serve as an electrically insulating layer is formed around aperiphery and beneath a bottom surface of the capacitor element 1.

In order to form lead out electrodes, blind holes 21 are formed by anetching, a laser machining and the like as FIG. 19 shows.

Electrodes 22 and 23 to electrically connect with the connectionterminals 8 and 9 from the blind holes 21, respectively, are formed by avacuum deposition, a sputtering, a plating and the like as FIG. 20shows.

And, for the purposes of an electrical insulation, a protection againstexternal stresses to the bottom surface of capacitor element 1, and alsoenhancing the reliability and the like, package 11 is further formed onthe previously applied package 11 by an injection molding of epoxy resinand the like. And external terminals 24 to electrically connect withlead out electrodes 22 and 23 formed on the periphery of capacitorelement 1 are provided, as FIG. 21 shows, to completing a solidelectrolytic capacitor.

As described above, according to a method of manufacturing solidelectrolytic capacitors in the present exemplary embodiment, solidelectrolytic capacitors with enhanced reliability are produced byapplying a little improvement to the already well established productionprocesses of a solid electrolytic capacitors employing an aluminum foiland a functional polymer.

Exemplary Embodiment 5

A description is given to a solid electrolytic capacitor in exemplaryembodiment 5 of the present invention with reference to FIG. 22 throughFIG. 29.

First, as FIG. 22 shows, a mixture of tantalum powder and a binder iskneaded and molded to a sheet-like shape. After subjected to a binderelimination process, the sheet-like molded shape is sintered at apredetermined temperature to obtain sheet-like shaped porous tantalumsintered body 19.

Next, as FIG. 23 shows, resin material 20 such as epoxy resin and thelike is impregnated at positions where electrode portion 2 is formed andalso resist layer 18 is formed by printing at positions where electrodeexposure area 25 is formed. Then, the resin material 20 and the resistlayer 18 are cured.

Thereafter, as FIG. 24 shows, the tantalum sintered body 19 is subjectedto an anodization process in a forming solution to form dielectric layer4 on the porous sections except the areas for electrode portion 2.

Subsequently, as FIG. 25 shows, a resin layer is formed by a printingand the like method around resist layer 18 as mentioned above to forminsulating section 7 and then, in the same manner as in exemplaryembodiment 4, solid electrolyte layer 5 composed of polypyrrole isformed on the dielectric layer 4.

Then, as FIG. 26 shows, collector layer 6 comprising a carbon layer, asilver paste layer and the like is formed on the solid electrolyte layer5.

The resist film 18 is removed as FIG. 27 shows and then, as FIG. 28shows, first connection terminal 8 and second connection terminal 9 areformed on the electrode exposure area 25 and the collector layer 6,respectively to form a capacitor element. The connection terminals areformed by any one layer of electrode materials such as gold, silver,copper, nickel and the like on an outer surface of the electrode portion2 (i.e. electrode exposure area 25) by the methods such as a vacuumdeposition, a sputtering, a plating and the like. The connectionterminals 8 and 9 are separated and insulated by the insulating section7.

Finally, as FIG. 29 shows, package 11 is formed by injection molding ofepoxy resin and the like, thereby completing the production of a solidelectrolytic capacitor.

By employing sheet-like tantalum sintered body 19 as described above, asolid electrolytic capacitor with a higher capacitance can be producedin comparison with the solid electrolytic capacitor employing aluminumfoil as described in exemplary embodiment 4 of the present invention.

Exemplary Embodiment 6

A description is given to a solid electrolytic capacitor in exemplaryembodiment 6 of the present invention with reference to FIG. 30 and FIG.31.

In FIG. 30 and FIG. 31, capacitor element I comprises valve metal sheet3, which is made porous except the areas where a plurality of electrodeportions 2 are located, dielectric layer 4 formed on a surface of theporous portion of the valve metal sheet 3, solid electrolyte layer 5formed on the dielectric layer 4, collector layer 6 formed on the solidelectrolyte layer 5, and insulating section 7 disposed between electrodeexposure area 25 on a surface of the electrode portion 2 and thecollector layer 6.

Although capacitor element 1 functions well even with the foregoingstructure, it is preferred that an additional metal layer is formed onthe electrode exposure area 25 to provide first connection terminal 8,and another additional metal layer is formed on the collector layer 6surrounding the insulating section 7 to provide second connectionterminal 9. Two of the capacitor element 1 thus structured are laminatedwith the first connection terminals 8 of one capacitor element connectedto the first connection terminals 8 of another capacitor element bymeans of interlayer connecting material 10 of solder and the like. Andalso the second connection terminals 9 of one capacitor element areconnected to the second connection terminals 9 of another capacitorelement by means of interlayer connecting material 10 of solder and thelike. And package 11 composed of epoxy resin and the like is formedaround the periphery of the laminated body by molding, thereby producinga solid electrolytic capacitor. The structure of the capacitor element 1and the materials used therein are the same as in exemplary embodiment 1of the present invention.

The solid electrolytic capacitor structured as above has a plurality ofconnection terminals 8 and also connection terminals 9 on and beneath anupper and a bottom surfaces thereof as FIG. 30 and FIG. 31 show, therebyallowing a semiconductor device to be mounted on one surface thereof andanother surface to be connected to a land of a circuit board.

At this time, the number of connection terminals 8 and 9 is made a sameas or to exceed a number of connection bumps of the semiconductordevice.

When the number of connection terminals 8 and 9 on one surface of thesolid electrolytic capacitor exceeds the number of the connection bumpsof the semiconductor device, chip components such as chip resistors,chip capacitors, chip inductors and the like are mounted thereon inaddition to the semiconductor device, thereby allowing the wholeassembly to be a kind of circuit module.

Thus, by making a solid electrolytic capacitor having a multi-layerstructure, a higher capacitance can be obtained. At the same time, byhaving connection terminals 8 and connection terminals 9 disposedalternately, low ESR and low ESL as well can be obtained to allow theimpedance characteristics at high frequencies to be improved greatly,resulting in realizing a solid electrolytic capacitor of excellent highfrequency response.

Exemplary Embodiment 7

FIG. 5 is a top view of a solid electrolytic capacitor in exemplaryembodiment 7 of the present invention. FIG. 32 is a cross-sectional viewof the solid electrolytic capacitor of FIG. 5, FIG. 33 is across-sectional view of another solid electrolytic capacitor and FIG. 34is a cross-sectional view of still another solid electrolytic capacitor.

The fundamental structure of the solid electrolytic capacitor inexemplary embodiment 7 of the present invention is the same as inexemplary embodiment 6 except that connection bumps 13 and 14 composedof gold, solder or tin are provided on the first connection terminal 8and the second connection terminal 9 to facilitate the connection withthe semiconductor device. In order to keep the bump pitches ofconnection bumps 13 and 14 constant, insulating film 16 with opening 15provided at the places, where connection bumps 13 and 14 are formed, isformed and then connection bumps 13 and 14 are formed.

FIG. 32 shows a solid electrolytic capacitor prepared by laminating twoof the capacitor element 1 and FIG. 33 shows a solid electrolyticcapacitor prepared by laminating three of the capacitor element 1. Thesesolid electrolytic capacitors have connection bumps 13 and 14 providedon both respective surfaces.

In FIG. 33, as interlayer connecting material 10 to connect electrodeportions 2, any one material selected from the group consisting ofsolder, a conductive adhesive and an anisotropic conductive sheet isused, and as interlayer connecting layer to connect collector layers 6,a conductive adhesive is used.

Meanwhile, FIG. 34 shows a solid electrolytic capacitor prepared bylaminating three of the capacitor element 1 with connection bumps 13 and14 provided only on the upper surface of the multi-layer capacitor. Thebottom surface thereof is covered by package II, thereby allowing themulti-layer capacitor to be mounted on a circuit board with a highdensely wiring patterns while an electrical insulation being maintained.

As described above, the solid electrolytic capacitor in the presentexemplary embodiment facilitates the mounting of the semiconductordevice thereon and also facilitates the mounting thereof on a circuitboard due to the provision of connection bumps 13 and 14 on connectionterminals 8 and 9, respectively.

Exemplary Embodiment 8

FIG. 9 is a cross-sectional view of capacitor element 1 in exemplaryembodiment 8 of the present invention.

The capacitor element 1 in the present exemplary embodiment includesvalve metal sheet 3 prepared by forming a tantalum powder into asheet-like shape followed by a sintering process. By preventing aforming solution from invading into a portion where electrode portion 2is formed, dielectric layer 4 is formed by anodization of the valvemetal sheet 3 except the area where the electrode portion 2 is formed.

Then, solid electrolyte layer 6 composed of a conductive polymer,manganese dioxide or the like is formed on dielectric layer 4. Further,collector layer 6 comprising carbon or a silver paste is formed on thesolid electrolyte layer 5, insulating section 7 is provided around theelectrode exposure area 25 on a surface of the electrode portion 2,first connection terminal 8 connected to the electrode exposure area 25is provided inside of insulating section 7 and second connectionterminal 9 connected to the collector layer 6 is provided around theinsulating section 7.

Up to these points, the structure described above is the same as inexemplary embodiment 3.

The necessary number of the capacitor element 1 thus prepared arelaminated in the same manner as in exemplary embodiment 6 and package 11is formed, thereby finishing the production of a solid electrolyticcapacitor.

The reason why a valve metal powder is used is to obtain a highercapacitance for the resulting solid electrolytic capacitor in comparisonwith the solid electrolytic capacitor employing capacitor element 1prepared by the use of valve metal sheet 3 composed of aluminum foil.

Exemplary Embodiment 9

First, in exemplary embodiment 9 of the present invention, one sheet ofsheet-like capacitor element 1 is first prepared according to the stepsshown in FIG. 10 through FIG. 21 in exemplary embodiment 4.

Then, as FIG. 35 shows, two of capacitor element 1 are aligned inposition to make positions of the first connection terminals 8 of thetwo capacitor element 1 to coincide with each other, and also to makepositions of the second connection terminals 9 of the two capacitorelement 1 to coincide with each other. Then, the two capacitor elements1 are laminated and connected electrically and also mechanically witheach other by means of interlayer connecting material 10, therebyobtaining a laminated body composed of two capacitor elements 1.

Finally, as FIG. 36 shows, for the purpose of electrical insulation andenhancing reliability by protecting the capacitor element 1 from thehumid environment and external stresses, package 11 composed of epoxyresin and the like is formed by injection molding around the laminatedbody of capacitor element 1 to complete a solid electrolytic capacitor.

As described above, according to the method of manufacturing solidelectrolytic capacitors in the present exemplary embodiment, solidelectrolytic capacitors with excellent reliability can be produced byapplying a little improvement to the established manufacturing processof a solid electrolytic capacitors employing a functional polymer and analuminum foil.

Exemplary Embodiment 10

First, in exemplary embodiment 10 of the present invention, one sheet ofcapacitor element 1 is prepared according to the steps as described inFIG. 22 through FIG. 29 in exemplary embodiment 5.

Then, as FIG. 37 shows, two of the capacitor element 1 thus structuredare laminated so as the positions of the first connection terminals 8 ofthe two capacitor elements 1 to coincide with each other and also thepositions of the second connection terminals 9 of the two capacitorelements 1 to coincide with each other, and the two capacitor elements 1are connected electrically and mechanically as well with each other bymeans of interlayer connecting material 10. And finally package 11composed of epoxy resin and the like is formed by an injection moldingaround a periphery of the laminated body of the capacitor elements 1 tocompleting a solid electrolytic capacitor.

As described above, by employing a method of using sheet-like tantalumsintered body 19, a solid electrolytic capacitors with a highercapacitance in comparison with the solid electrolytic capacitors usingaluminum foil as described in exemplary embodiment 9 of the presentinvention can be produced.

INDUSTRIAL USABILITY

A solid electrolytic capacitor of the present invention can produce amodule excellent in high frequency response since a direct mounting of asemiconductor device on the surface thereof is possible. Further, thesolid electrolytic capacitor of the present invention makes it possibleto realize a reduction in size while achieving a high capacitance.

What is claimed is:
 1. A solid electrolytic capacitor comprising: avalve metal sheet having a porous section; an electrode exposure areaformed on a surface of said valve metal sheet; a dielectric layer foamedon said porous section of said valve metal sheet; a solid electrolytelayer formed on said dielectric layer; a collector layer formed on saidsolid electrolyte layer; and an insulating section to electricallyinsulate said electrode exposure area from said collector layer, whereinsaid electrode exposure area and said collector layer are located on asame surface of said valve metal sheet.
 2. The solid electrolyticcapacitor according to claim 1, wherein said valve metal sheet comprisesany one of aluminum foil and a sintered body of a valve metal powder. 3.The solid electrolytic capacitor according to claim 1, wherein saidelectrode exposure area is any one of an outer surface of a sinteredbody of a valve metal powder and an outer surface of a though holeformed in a sintered body of a valve metal powder.
 4. The solidelectrolytic capacitor according to claim 1, wherein said solidelectrolyte layer is at least one of a conductive polymer and manganesedioxide.
 5. The solid electrolytic capacitor according to claim 1,further comprising: a first connection terminal connecting to saidelectrode exposure area; and a second connection terminal connecting tosaid collector layer.
 6. The solid electrolytic capacitor according toclaim 1, wherein said electrode exposure urea, dielectric layer, solidelectrolyte layer, collector layer and insulating section are formed onboth surfaces of said valve metal sheet.
 7. The solid electrolyticcapacitor according to claim 6, further comprising: a first connectionterminal connecting to said electrode exposure area; and a secondconnection terminal connecting to said collector layer.
 8. The solidelectrolytic capacitor according to claim 7, wherein said firstconnection terminal and second connection terminal are formed on bothsurfaces of said valve metal sheet.
 9. The solid electrolytic capacitoraccording to claim 5, wherein said first connection terminal in any oneof additional metal layers formed on said electrode exposure area and ona roughened surface of said electrode exposure area.
 10. The solidelectrolytic capacitor according to claim 5, wherein said secondconnection terminal is a metal layer formed on said collector layer. 11.The solid electrolytic capacitor according to claim 5, wherein saidsecond connection terminal is a metal layer located in an opening ofsaid insulating section formed on said collector layer.
 12. The solidelectrolytic capacitor according to claim 5, wherein each of said firstconnection terminal and said second connection terminal is a connectionbump.
 13. The solid electrolytic capacitor according to claim 1, whereina cross-sectional area of an electrode portion inside said valve metalsheet is smaller than an area of said electrode exposure area.
 14. Thesolid electrolytic capacitor according to claim 1, further comprising apackage.
 15. A Method of manufacturing solid electrolytic capacitorscomprising the steps of: forming a resist layer on a portion of a valvemetal sheet surface, said portion being an electrode exposure a; forminga porous section in said valve metal sheet; forming a dielectric layeron said porous section; forming an insulating section around said resistlayer; forming a solid electrolyte layer on said dielectric layer; andforming a collector layer on said solid electrolyte layer.
 16. A methodof manufacturing solid electrolytic capacitors comprising the steps of:sintering a valve metal powder to form a valve metal sheet; forming adielectric layer in said valve metal sheet except an area to be anelectrode exposure area; forming an insulating section around saidelectrode exposure area; forming a solid electrolyte layer on saiddielectric layer; and forming a collector layer on said solidelectrolyte layer.
 17. The method of manufacturing solid electrolyticcapacitors according to claim 16, further comprising: providing athrough hole; and forming an electrode portion in said through hole. 18.A solid electrolytic capacitor comprising a laminate of a plurality ofcapacitor elements, each of said capacitor elements comprising: a valvemetal sheet having a porous section; an electrode exposure area formedon a surface of said valve metal sheet; a dielectric layer formed onsaid pots section of said valve metal sheet; a solid electrolyte layerformed on said dielectric layer; a collector layer formed on said solidelectrolyte layer; and an insulating section to electrically insulatesaid electrode exposure area from said collector layer, wherein saidelectrode exposure area and said collector layer are located on a samesurface of said valve metal sheet.
 19. The solid electrolyte capacitoraccording to claim 18, wherein electrode exposure areas of one of saidplurality of capacitor elements are electrically connected to electrodeexposure areas of other capacitor element, and collector layers of oneof said plurality of capacitor elements are electrically connected tocollector.
 20. The solid electrolytic capacitor according to claim 18,wherein said valve metal sheet comprise any one of aluminum foil and asintered body of a valve metal powder.
 21. The solid elect capacitoraccording to clam 18, wherein said electrode exposure area is any one ofan outer surface of a sintered body of a valve metal powder and an outersurface of a through hole formed in a sintered body of a valve metalpowder.
 22. The solid electrolytic capacitor according to claim 18,wherein said solid electrolyte layer is a conductive polymer.
 23. Thesolid electrolytic capacitor according to claim 18, further comprising:a first connection terminal connecting to said electrode exposure area;and a second connection terminal connecting to said collector layer. 24.The solid electrolytic capacitor according to claim 23, wherein saidfirst connection terminal and said second connection terminal are formedon both surfaces of said capacitor element.
 25. The solid electrolyticcapacitor according to claim 23, wherein said first connection terminalis any one of additional metal layers formed on said electrode exposurearea and on a roughened surface of said electrode exposure area.
 26. Thesolid electrolytic capacitor according to claim 23, wherein said secondconnection terminal is a metal layer formed on said collector layer. 27.The solid electrolytic capacitor according to claim 23, wherein saidsecond connection terminal is a metal layer located in an opening ofsaid insulating section formed on said collector layer.
 28. The solidelectrolytic capacitor according to claim 23, wherein each of said firstconnection terminal and said second connection terminal is a connectionbump.
 29. The solid electrolytic capacitor according to claim 19,wherein a material to electrically connect said electrode exposure areasof one of said plurality of capacitor elements to said electrodeexposure areas of other capacitor element and a material to electricallyconnect said collector layers of one of said plurality of capacitorelements to said collector layers of other capacitor element are any oneselected from a group consisting of a solder, a conductive adhesive, ananisotropic conductive adhesive and a conductive polymer.
 30. The solidelectrolytic capacitor according to claim 18, further comprising apackage.
 31. A method of manufacturing solid electrolytic capacitorscomprising: forming a resist layer on a portion of a valve metal sheetsurface, said portion being an electrode exposure area; forming a poroussection in said valve metal sheet; forming a dielectric layer on saidporous section; forming an insulating section around said resist layer;forming a solid electrolyte layer on said dielectric layer; forming acapacitor element by forming a collector layer on said solid electrolytelayer; and laminating a plurality of said capacitor elements withelectrode exposure areas of one of said plurality of capacitor elementsbeing electrically connected to electrode exposure areas of othercapacitor element, and collector layers of one of said plurality ofcapacitor elements being electrically connected to collector layers ofother capacitor element.
 32. The method of manufacturing solidelectrolyte capacitor according to claim 31, wherein said valve metalsheet is any one of aluminum foil and a sintered body of a valve metalpowder.
 33. The method of manufacturing solid electrolytic capacitorsaccording to claim 32, further comprising: providing a through hole insaid valve metal sheet; and forming an electrode portion in said throughhole.